Fabrication of high luminescent Mn doped CdS semiconductor nanoparticles

In this work we have synthesized bare and doped CdS nanoparticles and studied luminescence properties of these particles as an important II-VI semiconductor. The thermochemical method is used for synthesis of these nanoparticles. Thiols are usually used as the capping agent to prevent further growth. Na₂S₂O₃ was used as the sulfur precursor, 3CdSO₄.8H₂O as the Cadmium precursor, Thioglycolic acid (TGA) as capping agent and Mn(NO₃)₂.4H₂O as Manganese doping precursor in thermochemical and room temperature growth. The application of TGA as capping agent instead of TG was studied as a novel idea in this research and was used practically in the synthesis of semiconductor nanoparticles. Using this process resulted in particles with sizes between 3-7nm. Several samples were synthesized and characterized under various conditions such as variation of Mn ions doping ratio, different temperatures, and different TGA concentrations. Synthesis of CdS nanoparticles with large Mn ions concentration resulted in decrement of their luminescence. In other words luminescence of nanoparticles was increased by decreasing Mn:Cd doping ratio. In this work synthesized nanoparticles under different doping ratios, and two samples which had the best results were Mn:Cd=1:80 and Mn:Cd=1:160 respectively. The particles growth under various temperatures indicated that decreasing temperature resulted in small particles, but their luminescence intensity fell down because of dominance of Mn emission in low temperatures. Also the results of particles growth under various TGA concentrations indicate the decrement of particles size distribution with increase of TGA concentration.